I say this with obvious fingers crossed:
http://service1.symantec.com/SUPPORT/sharedtech.nsf/docid/2002020506493713?Open&src=&docid=2001082413371406&nsf=nav.nsf&view=docid&dtype=∏=&ver=&osv=&osv_lvl=
That's what Symantec says on their site, and after a google search, seems it's been an issue before.
And here is what MS says about the error I was receiving:
http://www.microsoft.com/technet/prodtechnol/winxppro/reskit/prmd_stp_ottj.asp
I de-installed my Norton Suite, and SYMTDI.SYS was removed from the drivers folder. Rebooted and installed the base Norton Anti-Virus, which replaced SYMTDI.SYS and I had the same rebooting problem, with the exact same BSOD pointing to that driver. De-installed again and ran without Norton installed with no problems at all. Purchased McAfee Anti-Virus and installed, with no problems at all during multiple flights.
Of course now that I've said this, it'll start crashing again :lol:
At least it doesn't appear to be WideFS or FSUIPC related, which is a relief. Anyway, sorry for wasting forum space, but just troubleshooting. Thanks again Pete!